According to most scientists, activities like fossil fuel burning and deforestation have affected the global carbon cycle.

a.true

b.false

Which of the following processes does NOT add carbon to the atmosphere?

a.volcanic eruptions

b.respiration

c.weathering of limestone

d.subduction

Although direct measurements of atmospheric carbon dioxide have only been taken consistently since the 1950s, scientists have been able to retrieve data from the past 500,000 years. They have been able to do this by looking at

a.ice cores from ice sheets

b.sediment cores from the ocean

c.tree rings

d.all of the choices

A net carbon source is a carbon pool which takes in more carbon than it releases.